Quote:
Originally Posted by ACS
Mine still has the original Y pipe. What’s going to happen to it?
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IF it has a double wall pipe, the inner wall can collapse and block off the exhaust flow. Symptoms are crappy performance and carbs that keep going bad. My dad bought what is now my 75 in 78. Its performance sucked. It had problems going faster then about 60(during the 55 speed limit era). Plus the carb kept going bad and flooding out. The thing looked like a diesel going down the road. When the thermostat stuck shut, the head gasket cracked. Turned out to be a good thing. While the heads were off, I looked down the exhaust pipes and noticed that both were blocked off even though the outside looked normal. Took it to an exhaust shop and they said they had seen several of the newer GM trucks with that problem. Swapped to a dual exhaust and suddenly it ran much better. 90+ with more left(younger and stupider).
Don't know if the double wall Y-pipe was a converter thing to keep the exhaust hotter or a noise thing. Mine never had cats being a HD version but I can see GM using the same Y-pipe on both versions.